Laminated Polyester Adhesive Sheet with Crosslinked Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Pressure-sensitive adhesives face a challenge in achieving a balance between high heat resistance and adhesive force, as these characteristics are typically contradictory and difficult to satisfy simultaneously.
Innovation Solution
A pressure-sensitive adhesive sheet with a laminate structure comprising two crosslinked polyester resin layers, one with a higher weight-average molecular weight (LA) for adhesive force and another with a lower weight-average molecular weight (LB) for heat resistance, where the layer LA is exposed on the surface and layer LB is on the back, utilizing a tri- or more-functional isocyanate as a crosslinking agent, and specific polycarboxylic acid and polyalcohol components for enhanced interlayer adhesiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyester-based adhesive with higher molecular weight is used to improve adhesive force, then adhesive force increases, but heat resistance deteriorates
Solution Approach 1:
The adhesive layer is divided into multiple layers with different molecular weights. The lower molecular weight layer (0.2×10^4 to 1×10^4) provides heat resistance, while the higher molecular weight layer (4×10^4 to 12×10^4) provides adhesive force. This segmentation allows each layer to optimize its function without compromising the other.
Solution Approach 2:
The invention creates a composite adhesive structure by combining polyester resins with different molecular weights in a laminated configuration. This composite approach enables the adhesive to simultaneously exhibit both high heat resistance (from the low Mw layer) and high adhesive force (from the high Mw layer), resolving the contradiction between these two properties.
2Temperature
If crosslinking density is increased to improve heat resistance, then heat resistance improves, but adhesive force deteriorates
Solution Approach 1:
Different regions of the adhesive layer are assigned different crosslinking densities and molecular weights. The layer in contact with the substrate (higher Mw layer) maintains optimal adhesive properties, while the inner layer (lower Mw layer) provides heat resistance. This local differentiation resolves the contradiction by allowing each region to optimize for its specific function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves a good balance of high heat resistance and adhesive force, ensuring the pressure-sensitive adhesive sheet maintains both properties effectively.
Implementation Method 1
wherein at least one surface of the pressure-sensitive adhesive layer is formed of the layer LA and the layer LB is disposed on the back of the layer LA that constitutes the surface of the pressure-sensitive adhesive layer
Data Source
AI summary
The present invention has an object to provide a pressure-sensitive adhesive sheet provided with a polyester-based pressure-sensitive adhesive layer and capable of realizing heat resistance and adhesive force both on high levels. The pressure-sensitive adhesive sheet provided by the present invention contains a pressure-sensitive adhesive layer (21) that contains a polyester resin as a main component. The pressure-sensitive adhesive layer (21) having a laminate structure that contains at least one layer LA (two layers here, sign 214 and 216) where a polyester resin EA having Mw of from 4 x 104 to 12 x 104 is crosslinked; and at least one layer LB (one layer here, sign 212) where a polyester resin EB having Mw of from 0.2 x 104 to 1 x 104 is crosslinked. At least one surface of the pressure-sensitive adhesive layer (21) is constituted by the layer LA (sign 214 or 216).